Racks · usage conditions. The table below contains the assumptions estab-lished for various...

Racks

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The Catalog Number for KHK stock gears is based on the simple formula listed below. Please order KHK gears by specifying the Catalog Numbers.Racks

K R G F 2 - 500 HGear teeth induction hardenedTotal Length (500mm)Module (2)Other Products (End Machined)Other Products (Ground Gears)Type (Rack)Material (SCM440)

(Example) Material Other InformationM SCM415K SCM440 F Racks with Machined EndsS S45C D Racks with Bolt HolesSU Stainless Steel K Racks with Drill HolesBS Brass G Ground GearsP MC901 H Gear teeth induction hardenedD Polyacetal

TypeR RacksRH Helical RacksRO Round RacksS Spur Gears

MRGF/MRGFDHardened Ground Racks

m1.5 ～ 3 98

Heat Treatment: Tooth area carburized

Precision: KHK 1Material: SCM415

KRGF-H/KRGFD-HHardened Ground Racks

m1.5 ～ 3 Page 200

Heat Treatment: Thermal refined / gear teeth induction hardened


KRG/KRGF/KRGDThermal Refined Ground Racks

m1 ～ 3 Page 202

Heat Treatment: Thermal refined


SRRacks

m0.5 ～ 10 Page 216

Precision: KHK 4Material: S45C

SRFSteel Racks with Machined Ends

m0.5 ～ 10 Page 217


SUR/SURF/SURFDStainless Steel Racks

m1 ～ 4 Page 220

Heat Treatment: Solution treated

Precision: KHK 5Material: SUS304

PR/PRFPlastic Racks

m1 ～ 3 Page 224

Precision: KHK 5Material: MC901

BSRRacks

m0.5 ～ 1 Page 225

Precision: KHK 4Material: Free cutting brass (C3604)

Round Racks

m1 ～ 6 Page 226

SRO/SROS


SUROStainless Steel Round Racks

m1 ～ 3 Page 227

Precision: KHK 5Material: SUS303

DRMolded Flexible Racks

m0.8 ～ 2 Page 228

Precision: KHK 8Material: Duracon (M25-44)

SSDR/ARL/SRSPinions/Rack Guide Rails

Rack Clamps

Page 228

For Molded Flexible Racks

Precision: N8Material: S45C

SRH/SRHF/SRHFDHelical Racks

m2, 3 Page 232


SRHEFHelical Racks

m1.5 ～ 6 Page 234


New

Catalog Number of KHK Stock Gears

Series Series

SRG/SRGF/SRGFD/SRGFK

m0.5 ～ 6 Page 204

Hardened Ground Racks

Heat Treatment: Gear teeth induction hardened


Series

m1.5 ～ 5

KRF-H/KRFD-HHardened Racks

Page 206

Heat Treatment: Thermal refined / gear teeth induction hardened


Series

m1.5 ～ 6

SRF-H/SRFD-HHardened Racks

Page 208

Heat Treatment: Gear teeth induction hardened


Series

m1.5 ～ 6

SRF-HL/SRFD-HLLaser Hardened Racks

Page 210

Heat Treatment: Gear teeth laser hardened


Series

KRF/KRFDThermal Refined Racks

m1.5 ～ 5 Page 212



Series

DRF/DRFD/DRFKPlastic Racks

m1 ～ 3 Page 222

Precision: KHK 5Material: Polyacetal

Series

m1.5 ～ 4

SRAF/SRAFD/SRAFKRacks

Page 214


Series

SRFD/SRFKSteel Racks with Bolt Holes

m0.5 ～ 6 Page 218


Series

KRHG/KRHGF/KRHGFDGround Helical Racks

m1 ～ 3 Page 230



Series

SHEHelical Gears

m1.5 ～ 6 Page 234

Precision: N8Material: S45C

New

188 189

■ Rack Drive Linear Guide ■ Film Sealer

Example of table moving device that uses rack & pinion SR rack used for positioning

Racks Racks

KHK stock racks are made for high precision linear motion applications. We offer a large selection of racks ranging from module 0.5 to 10 and lengths from 100 to 2000 mm. The following table lists the main features.

Features

Catalog NumberNote 1 Module

Total length mm Parentheses

show no. of teethMaterial Heat

Treatment

Tooth Surface Finish

Gear accuracy KHK R 001 Note 3Parentheses show

JIS B 1702-1

Features

MRGF/MRGFD 1.5 to 3 500 SCM415 Tooth area carburized Ground 1

A ground rack made of carburized chromoly steel.Our highest-performance rack, with accumulated pitch error of 10μm or less. J Series products are also available.

KRGF-HKRGFD-H

1.5 to 3 500, 1000 SCM440Thermal refined, gear teeth induc-tion hardened

Ground 1 Heat treated ground gears with high precision and strength has ex-cellent cost-performance ratio. J Series products are also available.

KRG/KRGFKRGD

1 to 3 100, 500, 1000 SCM440 Thermal

refined Ground 1 High strength and abrasion-resistant for precision linear motion.

SRG/SRGFSRGFD/SRGFK

0.5 to 6 100, 300, 500, 1000 S45C Gear teeth induction

hardened NOTE 2Ground 3 Reasonably priced ground racks with abrasion-resistant

characteristics. J Series products are also available.

KRF-H/KRFD-H 1.5 to 5 1000 SCM440Thermal refined, gear teeth induc-tion hardened

Cut 5 A high-strength, long-life, tough hardened rack suitable for compact designs. J Series products are also available.

SRF-HSRFD-H

1.5 to 6 1000 S45C Gear teeth induction hardened Cut 5 Stable hardened racks with high strength, long life span

are reasonably priced. J Series products are also available.SRF-HLSRFD-HL 1.5 to 6 1000, 1500,

2000 S45C Gear teeth laser hardened Cut 4 Hardened racks with high strength due to the laser hardened tooth

surfaces and with a low price tag. J Series products are also available.

KRF/KRFD 1.5 to 5 500, 1000 SCM440 Thermal refined Cut 4 Increased strength with SCM440 material which is

thermal refined. J Series products are also available.

SRAF/SRAFDSRAFK

1.5 to 4 1000 S45C — Cut 4This gear rack has the same tooth height and face width sizes, more compact and reasonably priced in compari-son to SRF Racks J Series products are also available.

SR/SRFSRFD/SRFK

0.5 to 10 100, 300, 500, 1000, 1500, 2000 S45C — Cut 4 Low cost, large selections of modules and number

of teeth. J Series products are also available.SUR/SURFSURFD

1 to 4 500, 1000 SUS304 Solution treated Cut 5 Suitable for food machinery due to SUS304’s rust

resistant qualities.DRF/DRFD DRFK 1 to 3 500, 1000 Polyacetal — Cut 5 Plastic racks with little dimensional change, absorb lesser wa-

ter than MC Nylon racks. J Series products are also available.

PR/PRF 1 to 3 500, 1000 MC901 — Cut 5 Light-weight products made of MC Nylon can be used without lubrication.

BSR 0.5 to 1 300Free cutting brass (C3604)

— Cut 4 Small pitch racks made of free-cutting brass (C3604), excellent workability and high rust resistance.

SRO/SROS 1 to 6 500, 1000 S45C — Cut 4 Convenient in applications where the rack has the reciprocal motion. S Type is easy to install.

SURO 1 to 3 500, 1000 SUS303 — Cut 5 Same dimensions as SRO racks, except in stainless steel. Use where rust-resistance is required.

DR 0.8 to 2 2000 Duracon (M25-44) — Injection

Molded 8 Used in applications due to its flexibility, where metal racks do not have this attribute. Pinions and accessories are also available.

KRHG/KRHGF 1 to 3 100, 500, 1000 SCM440 Thermal

refined Ground 1 Excellent products with high precision and strength, and low noise and abrasion characteristics. J Series products are also available.

SRH/SRHFSRHFD

2 to 3 100, 500, 1000 S45C — Cut 5 Effective in reducing noise and vibration due to larg-

er contact ratio of helical gears.

SRHEF 1.5 to 6 1000 S45C — Cut 4 General-purpose helical racks with product dimensions and helix angle (19° 31’ 41”) according to EU specifications.

[NOTE 1] The catalog numbers in the above tables with a suffix of F have both ends machined so that they can be butted against each other to make any desired length. The items with (D) and (K) have mounting screw holes for easier assembly.

[NOTE 2] Products with module less than 0.8 are thermal refined, without their gear teeth being induction hardened.[NOTE 3] Precision grade standard of racks are set by KHK. Please see "Precision of Racks" in Selection Hints section for details.

● For safe handling and to prevent damage such as deformation, KHK stock racks have round chamfering at the corners of the top land of the gear tooth.This rounded chamfered shape is patented by KHK. It is also effective for reducing noise.

● Black products are KHK stock gears that have an applied black oxide coating for rust resistance;this “blackness” is a product characteristic of KHK stock gears.

SHE 1.5 to 6 (18 to 30) S45C — Cut (N8) A product designed so that the helix angle is 19° 31’ 41” and the distance of the pinion traveled in one turn is an integer (mm).

■ Racks

■ Pinion

KHK Technical Information

Application ExamplesKHK stock racks & pinions are adopted in driving devices for all kinds of linear motion systems, including transport devices.

■ Automatic packaging machine manufactured by Toyota Machinery Co., Ltd. ■ Dremax Long Strip Cutter

SUR stainless steel rack used for film winding tension part PR plastic rack used for feeding Long Strip Cutter

■ Lathe Auto Loader ■ Lathe Gantry Loader

SRO Round Rack used as a workpiece storage device (lifting/lowering table) KRG Ground Rack used as a workpiece conveying device

■ Packaging Machine

SR Rack used for label feeding SRO Round Rack used for extruders (can also become a lifting/lowering device by setting up vertically)


■ Extruder (design example)

* Not a design for machinery or a device in actual use.

Motor

Pinions

Round Rack

BaseBase

Sintered Metal Bushings

Sintered Metal Bushings

Extru

sion

190 191

Please select the most suitable products by carefully considering the characteristics of items and contents of the product ta-bles. It is also important to read all applicable "CAUTION" notes shown below before the final selection.

Selection Hints

① With the exception of helical racks, KHK stock racks can mate with any spur gears of the same module. Products with different tooth width can also be mated as a pinion.

② There are limited choices of mating gears for KRHG/KRHGF, SRHEF, and SRH Ground Helical Racks and Helical Racks. Be sure to check the helix direction (right or left) when selecting.

1. Caution in Selecting the Mating Gears

Allowable bending strength and surface durability values shown in product tables were computed by assuming a certain application en-vironment. They should be used as reference only. We recommend that each user computes their own values by applying the actual usage conditions. The table below contains the assumptions estab-lished for various products in order to compute gear strengths.

[NOTE 1] The gear strength formula is based on JGMA (Japanese Gear Manufacturers Association) specifications, "MC Nylon Technical Data" by Nippon Polypenco Limited and "Duracon Gear Data" by Polyplastic Co.

The units for the rotational speed (rpm) and the stress (kgf/mm2) are adjusted to the units needed in the formula.[NOTE 2] The allowable bending stress at the root σFlim is calculated from JGMA401-01, and set to 2/3 of the value in the consideration of the use of planetary-, idler-,

or other gear systems, loaded in both directions.[NOTE 3] For SRG, or SRGF Ground Racks, with a module less than m0.8, the allowable bending stress and allowable hertz stress are respectively 24.5 (kgf/mm2) and 62.5 (kgf/mm2).[NOTE 4] The values for DR m 1.5 racks were assumed by KHK. Usage conditions for SSDR (DR Rack Pinion) are the same as for the SSCP Pinion, shown on Page 241.

2. Caution in Selecting Gears Based on Gear Strength

Pinion (L) & Rack (R)

Pinion (R) & Rack (L)

■ Mating Helical Gear Selection Chart ( ○ Allowable × Not allowable)

Catalog Number

Item

MRGFMRGFD

KRGF-HKRGFD-H

KRF-HKRFD-H

KRG/KRGFKRGD/KRHG

KRHGF/KRHGFD

KRF/KRFD

SRG/SRGFSRGFD/SRGFKSRF-H/SRFD-H

SRF-HLSRFD-HL

SRAF/SRAFDSRAFK/SR/SRF

SRFD/SRFK/SRO SROS/SRH/SRHF

SRHFD/SRHEF

SURSURF

SURFDSURO

BSR SHEDRF

DRFDDRFK

PRPRF DR

Formula NOTE 1 Formula of spur and helical gears on bending strength (JGMA401-01) The Lewis formulaNo. of teeth of mating gears 30 Racks (30)Rotational speed 100rpm (100 rpm)Design life (durability) Over 107cycles Allowable bending stress (kgf/mm2)Impact from motor Uniform load

1.0 (40℃

with No Lubrication)

1.15 (40℃

with No Lubrication)

m 0.8 4.0m 1.0 3.5m 1.5 1.8 NOTE 4m 2.0 1.2(40℃ with Grease Lubrication)

Impact from load Uniform loadDirection of load BidirectionalAllowable bending stress at root σHlim (kgf/mm2) NOTE 2 47 32 20 NOTE 3 10.5 4 30Safety factor SF 1.2

Formula NOTE 1 Formula of spur and helical gears on surface durability (JGMA402-01)Kinematic viscosity of lubricant 100cSt (50℃)Gear support Supported on one end.Allowable Hertz stress σHlim (kgf/mm2) 166 112 79 90 NOTE 4 80 52.5 41.3 - 49 112Safety factor SH 1.15

■ Calculation of Bending Strength of Gears

■ Calculation of Surface Durability (Except where it is common with bending strength)

Catalog Number and Direction of

Helix

KRHGKRHGF

SRHEFSRH/SRHF

SRHFDRH LH RH RH LH

KHGLH ○ × × × ×RH × ○ × × ×

SHE LH × × ○ × ×

SHLH × × × ○ ×RH × × × × ○

Racks Pinions Racks

Racks Racks KHK Technical Information

The most important factor in selecting gears is the gear strength.

■ Definition of Bending Strength of Gears

The allowable bending strength of a gear is defined as the al-lowable tangential force at the pitch circle based on the mutu-ally allowable root stress of two meshing gears under load.

Example of failure due to insufficient bending strength

■ Definition of Surface Durability

The surface durability of a gear is defined as the allowable tan-gential force at the pitch circle, which permits the force to be transmitted safely without incurring surface failure. The allowable gear tooth load of a gear is defined as the allowable tangential force at the pitch circle based on the mutual gear tooth strength of two meshing gears under load.

Example of wear due to insufficient surface durability

Step 1 Determine the actual load torque applied to the gear and the gear type suitable for the purpose.

Step 2 Select provisionally from the allowable torque table of the Master Catalog based on the load torque.

■ For provisional selection from the Master Catalog

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Specifications

Precision grade KHK R 001 grade 1

Gear teeth Standard full depth

Pressure angle 20°

Material SCM440

Heat treatment Thermal refining only

Tooth hardness 225～ 285HB

Catalog No. Module No. of teeth ShapeTotal length Face width Height Height to pitch line Mounting hole dimensions No. of

mounting holes

Mountingscrew sizeA B C D E F G

KRGD1-500KRGD1.5-500KRGD2-500KRGD2.5-500KRGD3-500

m1m1.5m2m2.5m3

159106

806453

RDRDRDRDRD

499.51499.51502.65502.65499.51

1015202530

1520253035

1418.52327.532

68

101214

39.7539.7541.3241.3239.75

140140140140140

44444

M4M5M6M8M10

Catalog No. Module No. of teeth ShapeTotal length Face width Height Height to pitch line Allowable force (N) Allowable force (kgf) Weight

(kg)A B C D Bending strength Surface durability Bending strength Surface durability

KRGF1-1000 KRGF1.5-1000KRGF2-1000KRGF2.5-1000KRGF3-1000

m1m1.5m2m2.5m3

318212160128106

RFRFRFRFRF

999.03999.03

1005.311005.31

999.03

1015202530

15 20253035

1418.52327.532

1530345061309580

13800

6411440256040105770

156352625977

1410

65.3147261408588

1.492.183.635.437.53

Catalog No. ModuleEffective

no. of teethShape

Total length Face width Height Height to pitch line Allowable force (N) Allowable force (kgf) Weight

(kg)A B C D Bending strength Surface durability Bending strength Surface durability

KRG1-100KRG1-500 m1 29

159 R1 98505 10 15 14 1530 641 156 65.3 0.11

0.55KRG1.5-100KRG1.5-500 m1.5 20

105 R1 101505 15 20 18.5 3450 1440 352 147 0.22

1.10KRG2-100KRG2-500 m2 14

79 R1 98505 20 25 23 6130 2560 625 261 0.35

1.82KRG2.5-100KRG2.5-500 m2.5 11

63 R1 100505 25 30 27.5 9580 4010 977 408 0.54

2.73KRG3-100KRG3-500 m3 9

52 R1 101505 30 35 32 13800 5770 1410 588 0.76

3.81

SW: Sawing surface

[Caution on Secondary Operations] ① Please read “Caution on Performing Secondary Operations” (Page 196) when performing modifications and/or second-ary operations for safety concerns. KHK Quick-Mod Gears, the KHK's system for quick modification of KHK stock gears is also available.

[Caution on Product Characteristics] ① The allowable forces shown in the table are the calculated values according to the assumed usage conditions. Please see Page 192 for more details.

② The backlash of racks differ depending on the size of the mating pinion. Please calculate the backlash from the backlash value of the mating pinion. Also, please refer to the data in the section called 'Backlash of Rack Tooth (Amount of Tooth Thinning)' on Page 195.

③ After attaching the racks to the base, please fasten with dowel pins. Clamping only with mounting screws could possibly cause the screws to be broken, due to a heavy load. For details, please see the assembly method to the mounting base on Page 197.

Module 1～ 3KRG・KRGF・KRGD

Thermal Refined Ground Racks

Step 3 We recommend that each user computes their own values by applying the actual us-age conditions to determine the suitability of the gear strength.

Calculate the strength formally using the vari-ous gear strength formulas.Please see Page 71 of our technical reference book for more details.

Strength confirmation is simple when using the website.

When selecting KHK standard gears, glance over the Cautions on Product Characteristics and Cautions on Performing Secondary Operations in the respective dimension tables.

① Products not listed in this catalog or materials, modules, number of teeth and the like not listed in the dimensional tables can be manufactured as custom items. Please see Page 16 for more details about custom-made orders.

② The color and shape of the product images listed on the dimension table page of each product may differ from the actual product. Be sure to confirm the shape in the dimension table before selection.

③ The details (specifications, dimensions, prices, etc.) listed in the catalog may be changed without prior notice. Changes are announced on the KHK website. Website URL: https://khkgears.net/ Overseas Sales Department: TEL: 81-48-254-1744 FAX: 81-48-254-1765 E-mail: [email protected]

(2) Bending strength formula

(10.4)

(10.5)

(10.6)

(10.7)

(3) Calculating various coefficients

In order to satisfy the bending strength, the nominal circum-ferential force Ft on the meshing pitch circle must be less than or equal to the allowable circumferential force Ftlim on the meshing pitch circle calculated by the permissible bending stress at root.

Alternatively, the bending stress at root σF obtained from the nominal circumferential force Ft on the meshing pitch circle must be less than or equal to the permissible bending stress at root σFlim.

The permissible circumferential force Ftlim (kgf) on the meshing pitch circle is obtained by the following equation.

The bending stress at root (kgf/mm2) is obtained by the following equation.

192 193

The precision standards of KHK stock racks are established by us.The table below indicates the tolerance ranges of our racks.

3. Cautions on Selecting Racks By Precision

■ Precision Grades of Racks (KHK R 001) Unit: μm

Grade

Pitch E

rror

Over m0.4 to 1CP2.5

Over m1 to 1.6CP5

Over m1.6 to 2.5－

Over m2.5 to 4CP10

Over m4 to 6CP15

Over m6 to 10CP20

Rack Length (nominal)

1000 or less

1001 up to 2000

1000 or less

1001 up to 2000

1000 or less

1001 up to 2000

1000 or less

1001 up to 2000

1000 or less

1001 up to 2000

1000 or less

1001 up to 2000

1

S.P.E. 10 － 10 12 11 12 11 13 13 14 14 16

T.T.E. 10 － 11 13 12 14 13 15 14 16 16 18

T.C.E. 28 － 29 33 30 35 32 37 35 40 40 45

2

S.P.E. 14 － 14 17 15 17 16 18 18 20 20 23

T.T.E. 16 － 16 19 17 19 18 21 20 24 24 27

T.C.E. 39 － 41 48 43 49 46 53 50 57 58 64

3

S.P.E. 20 － 20 24 21 25 23 26 25 29 29 32

T.T.E. 22 － 24 28 25 29 27 31 30 34 34 40

T.C.E. 56 － 57 67 60 70 64 74 71 80 81 91

4

S.P.E. 28 － 29 33 30 35 32 37 35 40 40 45

T.T.E. 33 － 34 42 38 43 40 46 44 50 51 57

T.C.E. 79 － 81 95 85 99 91 105 100 115 115 130

5

S.P.E. 39 － 41 48 43 49 46 53 50 57 58 64

T.T.E. 49 － 51 59 53 62 57 69 66 75 76 85

T.C.E. 110 － 115 135 120 140 130 145 140 160 160 180

8

S.P.E. 206 206 212 212 219 219 －－－－－－

T.T.E. 330 330 339 339 350 350 －－－－－－

T.C.E. －－－－－－－－－－－－

[NOTE] ① Since the pitch accuracy of racks may vary due to humidity, the precision grades are evaluated at the bottom surface of the product, at the temperature of 20℃ . The dimensions of the KHK PR Plastic Racks may vary widely due to humidity. Therefore, the total composite error is assumed to be excluded from this

accuracy standard. Please refer in our separate technical reference book to "Design of Plastic Gears" (Page 100) for change in dimensions.

② For the accuracy of CP Rack, convert CP to m (module) when reference is made to the data in the table. (m=CP/ π ).

■ Pitch inspection and a sample report using Karl Zeiss UMC-550 Coordinate Measuring Machine. (KHK R 001 Grade 1)

① Pitch Errors of Racks (KHK R 001)

Our precision grades for pitch errors are established by referring to JIS Standards. The precision grades are set from 1 to 8, in accordance with the tolerance of a single pitch error (S.P.E.), adjacent tooth-to-tooth error (T.T.E.), and the total composite error (T.C.E.) for each module and length.

Racks Racks KHK Technical Information

Less than 0.03mmMeasurement po-sition of extruded material1.0mm

Face width

■ Tolerance on Face Width and Height

Precision grade(KHK R 001)

Face widthGrade 1 Grade 2 Grades 3 to 5 *

6 or less

0－ 0.05

0－ 0.10

0－ 0.18

7 to 10 0－ 0.10

0－ 0.22

11 to 18 0－ 0.10

0－ 0.27

19 to 30 0－ 0.15

0－ 0.33

31 to 50 0－ 0.15

0－ 0.39

51 to 90 0－ 0.15

0－ 0.46

■ Maximum Curvature Values (Flatness Tolerance L)

[NOTE] Dimensional tolerance of hardened products is that prior to hardening.Dimensional tolerance for plastic racks is the value obtained when ma-chining is performed, and may increase slightly due to aging.* BSR products are not applicable.

Precision Grade(KHK R 001)

Length (nominal)Grades 1 & 2 Grade 3 Grades 4 & 5

500 0.05 0.1 0.2

1000 0.1 0.2 0.3

1500 －－ 0.3

2000 －－ 0.4

Product Type Module Dimensional Tolerance

F Type End Machined Product

m0.5 － 0.1－ 0.3

m0.8 (CP2.5) － 0.1－ 0.5

m1 up to 2.5 － 0.2－ 0.6

m2.5 or more － 0.2－ 0.8

FRCP and DR Flexible Racks Uniform ± 10

Products other than the above Uniform ＋ 3－ 2

[NOTE] The straightness tolerances of round racks are 0.15/500 mm and 0.2/1000 mm.Plastic racks change over time so are excluded from this precision standard.

■ Tolerance on Total Length

[NOTE] For Type-F racks with machined ends, the dimensional tolerance is a calculated value according to assumed usage conditions, without con-sideration of pitch errors and aged deterioration.

■ Backlash of Rack Teeth (Amount of Tooth Thinning)

Precision grade(KHK R 001)

Module (m)Pitch (CP)

Grade 1 & 2 Grade 3Grade 4 Grade 5

Excludes thermal refined racks Includes thermal refined racks Hardened Products Stainless Steel/Helical Racks Plastic Products

m0.5 － 0 to 0.07 0 to 0.08 －－－－m0.8, CP2.5 0 to 0.06 0 to 0.08 0 to 0.09 －－－－m1 0 to 0.06 0 to 0.10 0 to 0.11 －－ 0 to 0.13 0 to 0.20m1.5, CP5 0 to 0.06 0 to 0.10 0.04 to 0.13 0.04 to 0.15 0.02 to 0.17 0.04 to 0.15 0 to 0.21m2 0 to 0.06 0 to 0.10 0.05 to 0.14 0.05 to 0.16 0.03 to 0.18 0.05 to 0.16 0 to 0.22m2.5 0 to 0.06 0 to 0.10 0.06 to 0.16 0.06 to 0.18 0.04 to 0.20 0.06 to 0.18 0 to 0.24m3, CP10 0 to 0.06 0 to 0.10 0.07 to 0.18 0.07 to 0.20 0.05 to 0.22 0.07 to 0.20 0 to 0.27m4 － 0 to 0.10 0.08 to 0.22 0.08 to 0.24 0.06 to 0.26 0.08 to 0.24 －m5, CP15 － 0 to 0.10 0.09 to 0.24 0.09 to 0.26 0.07 to 0.28 0.09 to 0.26 －m6, CP20 － 0 to 0.10 0.10 to 0.28 － 0.08 to 0.32 －－m8 －－ 0.13 to 0.32 －－－－m10 －－ 0.15 to 0.34 －－－－

Unit: mm

[NOTE] The values shown in the table are amount of tooth thinning. The theoretical backlash of assembled rack and pinion is given by:

Amount of tooth thinning of the rack : See above tableAmount of tooth thinning of the pinion : Take 1/2 of backlash given in the product table

Rack & pinion backlash = Amount of tooth thinning of the rack + Amount of tooth thinning of the pinion

② Precision of Rack Blanks

③ Backlash of Rack Teeth

( )( )( )( )

Unit: mm

Unit: mmUnit: mm

Note) Some products use an extruded material and the center of the 4 surfaces of the material may be slightly dented.

194 195

Racks Racks

In order to use KHK stock racks safely, carefully read the Application Hints before proceeding. If there are questions or you re-quire clarifications, please contact our technical department or your nearest distributor.▪ TEL: 81-48-254-1744 FAX: 81-48-254-1765 E-mail: [email protected]

① Secondary operations can be performed on all KHK stock racks except for the racks with their gear teeth induction hardened. To avoid problems of gear precision, do not reduce the face width. The precision of ground racks and racks with mounting holes may drop if you do not exercise extreme caution during installation or while modifying.

② Pitch lines of racks are controlled by using the bottom sur-face as the reference datum and over-pin measurements on tooth thickness. If you machine the bottom surfaces, the precision of the racks may be affected.

③ When connecting two racks, the machining of the mat-ing ends requires careful consideration in terms of the pitch (p) accuracy. The meshing will be poor if the pitch straddling the connection has a positive tolerance. We recommend a minus tolerance on pitch of at the con-nection.The below is an indication of pitch tolerance for each module.

④ To use dowel pins to secure racks, attach the racks to the base and drill both simultaneously.

⑤ KHK stock racks made of S45C and SCM440 (except for ground racks) can be induction hardened. However, the precision of pitch is decreased.

⑥ To be able to handle parts safely, all burrs and sharp cor-ners should be removed after the secondary operations are done.

⑦ If you are going to modify the gear by gripping the teeth, please exercise caution not to crush the teeth by applying too much pressure. Any scarring will cause noise during operation.

① KHK stock racks are designed to give the proper normal direction backlash when assembled using the mounting distance given by the formula below (mounting dis-tance tolerance of H7 to H8 required). The backlash val-ues are given in the table on Page 193. Make sure that the mounting distance stays constant for the length of the rack.

② KRG type of KHK stock ground racks have four surfaces ground parallel with high precision. To maintain true angle, they should be mounted on high precision bases (within 10μm recommended) as shown below. It is even possible to correct for the angular errors of racks by com-pensating the mounting base. With recent increases in the requirement for zero backlash linear drives, such ac-curate assembly as shown is becoming more important.

③ If the racks are not secured properly to the base, they could shift during operation and cause unexpected problems.It is very important to insure firm mounting by the use of dowel pins or similar devices.

④ Machined end type racks such as SRF and SRFD series have the pitch tolerance of -0.05 to -0.4mm at the end face. If you try to connect the racks without any space, the pitch at the connection will be too small and will cause problems. Please follow the following diagrams for assembly.

⑤ With SRFD etc., if using more than 10 racks connected together to form a rack with mounting holes machined along a length of 1 meter, the pitch precision and ma-chining precision may cause the rack and base mount-ing holes to deviate, leading to set screw interference with the counterbored hole and preventing mounting. When using a rack for long lengths such as 10 meters or 20 meters, have the mounting holes additionally ma-chined into long holes.

Pinion

Rack

Application Hints

2. Cautions on Performing Secondary Operations

3. Points of Caution during Assembly

Mounting distance a = Height of pitch line of rack + Pitch radius of pinion

[NOTE] Pinions are assumed to be stan-dard stock spur gears (x=0).

Module Pitch (p) Tolerance

m0.5 1.57 － 0.05－ 0.15

m0.8 2.51 － 0.05－ 0.25

m1 3.14－ 0.1－ 0.3m1.5 4.71

m2 6.28m2.5 7.85

－ 0.1－ 0.4

m3 9.42m4 12.57m5 15.71m6 18.85m8 25.13m10 31.42

p = π·m p : Reference pitchπ : Pim : Module

Unit: mm

p

KHK Technical InformationSR2-100 (joining rack)

Mounting base

0.2 to 0.6SRFD2-1000

Reamer hole

SRFD2-1000

How to mount racks on a mounting base (For SRFD2-1000)

1. Pitch alignment Place SRFD2-1000 on the mounting base, align SR2-100 and temporarily tighten the bolt.

2. Securing to the mounting baseTap with a plastic hammer, bring it into close contact with the mounting base, and further tighten the bolt.(When using a metal hammer, be careful not to damage the gear teeth by using a stiffening plate, etc.)

3. Run the pinion and check the following ① Is there abnormal noise or vibration? ② Is the backlash appropriate? ③ Is there poor edge contact of gear teeth?

SRFD2-1000 is designed to have a gap of 0.2 to 0.6 mm.

SR2-100 (joining rack)

SRFD2-1000SRFD2-1000

Mounting base

Mounting base


4. Secure fixation to the mounting base We recommend that you tap the knock pin so that the rack does not shift due to vibration, etc. ① Simultaneously machine reamer holes

Mounting base


Drill

Knock pin ② Drive the knock pin

Mounting base


Tighten again after tapping the knock pin.It can be marked with a pen to find looseness.

Stiffening Plate

105.3

Dimensions Table F Value x 2

KHK considers safety a priority in the use of our products.When handling, adding secondary operations, assembling, and operating KHK products, please be aware of the following issues in order to prevent accidents.

Warning: Precautions for preventing physical and property damage

Caution Cautions in Preventing Accidents

1. When using KHK products, follow relevant safety regulations (Occupational Safety and Health Regulations, etc.).2. Pay attention to the following items when installing, removing, or performing maintenance and inspection of the product. ① Turn off the power switch. ② Do not reach or crawl under the product. ③ Wear appropriate clothing and protective equipment for the work.

1. Before using a KHK product, read the precautions in the catalog carefully in order to use it correctly.2. Avoid use in environments that may adversely affect the product.3. Our products are manufactured under a superior quality control system based on the ISO9000 quality management system; if you

notice any malfunctions upon purchasing a product, please contact the supplier.

Joining Rack

[NOTE] Joining gauge racks for helical racks must have the opposite hand from the racks. Please use 100 mm long racks as a joining gauge rack, or alternatively the rack of the same specifications on hand.

d1. Cautions on Handling

① KHK products are packaged one by one to prevent scratches and dents, but if you find issues such as rust, scratches, or dents when the product is removed from the box after purchase, please contact the supplier.

② Depending on the handling method, the product may be-come deformed or damaged. Long racks and resin racks deform particularly easily, so please handle with care.

4. Cautions on Starting

① Check the following items before starting. • Are the gears installed securely? • Is there uneven tooth contact? • Is there adequate backlash? Be sure to avoid zero-backlash. • Has proper lubrication been supplied?② If gears are exposed, be sure to attach a safety cover

to ensure safety. Also, be careful not to touch rotating gears.

③ Gears can be lubricated with the "grease lubrication method", "splash lubrication method (oil bath method)", or "forced lubrication method (circulation lubrication method)".

For initial operation, the lubricant may deteriorate markedly, so check the condition of the lubricant after starting.

For more technical information, please see the section "Gear Lubrication" (Page 112) of our technical reference book.

④ If there is any abnormality such as noise or vibration during startup, check the gears and assembly condition.

"High gear accuracy", "smooth gear teeth surface" and "correct tooth contact" are some of the measures against gear noise. For more technical information, please see the section "Gear Noise and Countermeasures" (Page 119) of our technical reference book.


Mounting base

0.2 to 0.6SRFD2-1000

Reamer hole

SRFD2-1000


1. Pitch alignment Place SRFD2-1000 on the mounting base, align SR2-100 and temporarily tighten the bolt.

2. Securing to the mounting baseTap with a plastic hammer, bring it into close contact with the mounting base, and further tighten the bolt.(When using a metal hammer, be careful not to damage the gear teeth by using a stiffening plate, etc.)

3. Run the pinion and check the following ① Is there abnormal noise or vibration? ② Is the backlash appropriate? ③ Is there poor edge contact of gear teeth?

SRFD2-1000 is designed to have a gap of 0.2 to 0.6 mm.



Mounting base

Mounting base


4. Secure fixation to the mounting base We recommend that you tap the knock pin so that the rack does not shift due to vibration, etc. ① Simultaneously machine reamer holes

Mounting base


Drill

Knock pin ② Drive the knock pin

Mounting base


Tighten again after tapping the knock pin.It can be marked with a pen to find looseness.

Stiffening Plate

105.3

Dimensions Table F Value x 2

As an example of Rack Joining, we recommend the following method.


196 197

Racks Racks

Laser Hardened Racks

● Lasers used for hardening gear teethIn this environmentally friendly hardening method, powerful light provides in-

stantaneous hardening and cooling water is not required due to diffusion of heat.

● Hardening is possible wherever laser irradiation isLasers excel at spot hardening. As long as the laser can be irradiated, even the

inside of bores can be hardened.

● Less distortion due to burning during hardeningAs the laser hardens necessary areas in spots, distortion due to burning can be

minimized.


Since racks are a simple mechanism, the material, hardening, strength and precision can be designed ac-cording to the environment.They are also inexpensive, with parts that can be purchased separately for replacement.In the designing process, please refer to Features of Racks & Pinions and Ball Screws in the table below.

Table

Stroke

Ball screw nutBall screw shaft

Support unit (support side)Nut bracket

Linear guide

Base

Motor

Support unit (fixed side)

CouplingMotor bracket

● Features of Racks & Pinions

Stroke

Base

Table Motor Motor

TableLinear guide

Motor bracket

Rack

Pinion Pinion Rack

Advantages Details

Few component parts Since it does not have parts such as balls and retainers, there is less risk of accidentally falling apart during assembly and disassembly.

Supports heavy loads Racks with large module can be used for heavy loads.

Compact products can be manufactured Since it can be made smaller than products with ball screws, it can be used compactly for light loads.

High transmission efficiency High transmission efficiency of about 98% (excluding lubrication oil stirring resistance and bearing resistance).

High feed speed If the pinion diameter is large, it supports high-speed feeding.

No length limit Screws can only be up to about 2 m to avoid excessive bending, but racks can be joined together and used at greater lengths.

Flexible production is available Materials, hardening, shapes and the like can be designed flexibly, allowing easy adjustment to the machine.

High-precision products can be manufactured Gear grinding can be provided to minimize pitch error.

Can be used for food-related machinery MC nylon and stainless steel products can be manufactured.

Disadvantages Details

Backlash is presentBacklash is required for smooth rotation.Backlash may become a problem in forward/reverse rotation positioning.

Lubrication is required Metal racks require lubrication. Plastic racks do not require lubrication at light loads, but their precision is lower.

● Features of Ball ScrewsAdvantages Details

High transmission efficiency Transmission efficiency of 90% or higher.

High-precision products can be manufactured High-precision ball screws can be manufactured by grinding.

High feed speed High-speed feed is possible with high-lead ball screws.

No backlash The use of pressure eliminates backlash.

Disadvantages Details

Length is limited Since the screw deflects, about 2 meters is the practical limit.

Hard to manufacture special products Since it is hard to manufacture special products, machines must be adjusted to the shape of the ball screw.

Lasers enable hardening

that barely changes the

precision grade.

Rack downsizing

Catalog Numbers (Comparison Example)

Material Heat TreatmentAllowable force kgf Precision

KHK R 001Series nominal total length mm

Bending strength Surface durability

SRF3-1000 S45C None (raw material) 879 186 Grade 4 300,500,1000,1500,2000

KRF3-1000 SCM440 Thermal refined 1410 421 Grade 4 500,1000

SRF3-1000HL S45C Laser hardened 879 407 Grade 4 1000,1500,2000

SRF3-1000H S45C Induction hardened 799 468 Grade 5 1000

KRF3-1000H SCM440Thermal refined / induction hardened

1280 725 Grade 5 1000

MRGF 3-500 (2 units) SCM415 Carburized 2070 1900 Grade 1 500

Comparison table per series (module 3, rack length: 1,000 mm)

The graph below simulates the downsizing of KHK stock racks. It is possible to reduce the module (size) with equivalent trans-mission power, or to reduce the price likewise. Please select a product that fits your needs.

The H Series, KHK stock racks with induction hardened gear teeth, and the HL Series, with laser hardening, are available.

Increased strength leads to smaller sizeSRF8-1000 39.7kgKRF4-1000H 12.9kgMass reduced ⇒ 26.8 kg

The surface durability can be increased by hardening the gear teeth. By increasing the strength thus, the angular dimensions of modules and racks can be re-duced. This helps reduce the cost.

■ Example of rack downsizing

■ Comparison table of permissible transmission force of hardened racks

* Please see Page 210 for products.

m8 rack angular dimension

75mm

75m

m

40mm

45m

mm4 rack angular dimension

0

500

1000

1500

2000

2500Surface durability

Hardened Rack SRF-H/KRF-H/SRF-HL SeriesConventional Rack SRF/KRF Series

Allowable force (kgf)

Comparison of Racks & Pinions and Ball Screws

Racks · usage conditions. The table below contains the assumptions estab-lished for various...

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Transcript of Racks · usage conditions. The table below contains the assumptions estab-lished for various...